Why are you keeping the factory head unit, navigation? They have TERRIBLE sound quality and using speaker level inputs will significantly increase the risk of introducing noise into your audio system. Personally I would avoid. You would be far better off purchasing an Alpine or Pioneer head unit that will do bluetooth hands free and buy a GPS to stick in the right hand corner of your windscreen. Better spot for viewing your navigation, and you will gain far more sound quality with a new deck.

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[I]trolololol[/I]